This invention relates to a printing plate mounting apparatus for releasibly connecting a printing plate to a rotary cylinder of a printing press and, more particularly, to such a mounting apparatus in which the plate is mounted by means of tail members at opposite ends which are held within a longitudinal mounting gap in the surface of the cylinder.
It is well known to mount a printing plate to a rotary cylinder of a printing press by means of tail members at opposite ends of the planar, flexible body of a printing plate which are releasibly held within a cavity beneath an elongate, longitudinal, mounting slot, or gap, in the surface of the cylinder.
The plate, or plate body, and the tail members, which are integrally formed therewith from rolled steel or other suitable material, have a thickness of approximately eight to twelve mils. With known printing plates of this type, the smallest gaps which can be used are at least ten times the thickness of the plates. Specifically, the smallest gap known to operate successfully is approximately 123 mils thick.
The gaps in the surface of a rotary cylinder tend to imbalance the cylinder which causes vibrations that can cause streaking at higher press speeds. It is well known that the larger the gap, the greater the vibration and the greater resultant streaking problem. Accordingly, many efforts have been made to reduce the gap to a smaller dimension than has so far been possible or to eliminate the gap entirely.
In known printing plate mounting assemblies, the tail members are both substantially planar and extend at acute angles to overlie the printing plate body. The tail at the leading edge is inserted in the gap and hooks around an edge. The flexible body is then wrapped around the cylinder until the tail at the opposite end of the body is located opposite the gap. It is then inserted in the gap alongside the leading edge tail member and locked in place.
With known printing plates, the gaps are so large, the locking mechanism often must longitudinally strain the tail member to keep it in place which can cause distortion of the tail member. This distortion is preferably avoided since it can cause jamming of the tail member within the slot and hinder or prevent subsequent removal even when the gap is relatively large. Even without distortion, attempts to reduce the gap to less than a minimum gap size of approximatley 123 mils results in difficulties in inserting the one tail member in the gap after the other tail has already been inserted. Moreover, small gap sizes can create unacceptable difficulties in removing the tail members after insertion with known printing plates.